Little is known for sure about these powerful explosions, although it is suspected that they are the product of the collapse of extremely massive stars or their collisions with superdense objects such as neutron stars. Both relationships also imply that hypernovae probably have something to do with the formation of black holes. Aside from the physics that I'm not going to butcher by trying to explain, these relationships have been deduced primarily from the locations of gamma ray bursts' points of origin as well as the locations of various remnants of hypernovae, which both tend to be in areas of intensive star formation. Said areas are also hotspots for the formation of neutron stars, black holes, and other associated objects.

Another hypernova that may come to play an important role in our lives in the near future is Eta Carainae. While it is not yet a hypernova, it is suspected that it will probably become one relatively soon due to its unstable patterns of brightness and dimness over the past 150 years that has culminated recently in an intensive brightening spell. It now radiates around 400 million times as much light and energy as the sun and is brightening in a way that astronomers do not understand. On the bright side, though, if it does explode again, it will probably be too far away (7500 light years) to hurt those of us who are protected from gamma ray bursts by an atmosphere. If, however, you are an orbital satellite or have any friends who are orbital satellites, I'd be very frightened indeed.

A really cool picture of Eta Carainae can be found at http://earthfiles.com/earth040.html, where I also got much of the information on it. Most of the rest of the information in this writeup comes from http://www.space.com/scienceastronomy/astronomy/astrobizarre_000928.html.

It should also be noted that I am the layest of lay persons when it comes to this stuff, so if I've gotten anything wrong, please /msg sludgeel so that I can correct it.